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Aquaponics, Hydroponics, and Aquaculture
Aquaponics is a food production system in which the waste produced by aquatic species supplies nutrients for plants grown hydroponically, which in turn purify and recycle the water. As urbanization claims more land, environmental concerns publicize the search for a safe, nutritious, ample and affordable food supply. Sustainable agriculture aims to advance common positions to protect our natural resources while innovating the use of developed, urban areas.National Sustainable Agriculture Coalition (2014). “Sustainability of Urban Agriculture.” Aquaponics provides a sustainable, financially viable food production system. The aquaponic system is based off the working model of the earth itself. It brings together aquaculture, the raising of fish in tanks, and hydroponics, the growing of plants in a soilless environment.Purdue University (2009). “Aquaponics.” YouTube. 2009-10-27. In this system, fish produce waste (i.e. ammonia), which can be utilized by naturally occurring bacteria and converted into nutrients needed by plants.Mensing, Blake M (2009). "Aquaponic & Landfill Methane Use." Sustainable Development Law & Policy 9.3. Bacterial metabolism is the process by which the waste is converted into useable nutrients.Purdue University (2009). “Aquaponics.” YouTube. 2009-10-27. This byproduct promotes healthy plant growth and, at the same time, filters the water.Purdue University (2009). “Aquaponics.” YouTube. 2009-10-27. The water, now clean, can be recycled into tanks, continuing the cycle. Aquaponic systems are scalable. They can range from small, individual systems to commercial operations inhabiting large indoor facilities. Because most aquaponic systems exist indoors, there is little or no environmental interference. However, this also means the initial investment costs more than traditional cage or pond farming. Initial investments range from $2,000 to approximately $100,000 depending on the size of the operation.Purdue University (2009). “Aquaponics.” YouTube. 2009-10-27. For every one gallon of water, users can have one-half to one-square-foot of grow space. Aquaponics uses approximately two percent of the water of a traditional farm. For every pound of fish, you need one to two gallons of water in a tank.Purdue University (2009). “Aquaponics.” YouTube. 2009-10-27. All proper husbandry practices apply. Upper Midwest states, like Minnesota, require an aquatic farm license subject to an acreage fee.“Aquatic Farm License” (2013). Minnesota Department of Natural Resources. Check your local DNR office for state-specific statues or regulations. The Fish System (Aquaculture) The aquaculture part of the system relies on careful control of the fish’s environment year round. Water quality needs to be maintained and carefully monitored. The temperature of the system is dependent on selected species and should be monitored via a thermostat.Purdue University (2009). “Aquaponics.” YouTube. 2009-10-27. Consistent testing ensures a healthy, disease-free environment for fish to grow.Mensing, Blake M (2009). "Aquaponic & Landfill Methane Use." Sustainable Development Law & Policy 9.3. As a result, access to electricity and a water supply is necessary for the system’s success. Because water is recirculated, it is only lost when being absorbed by plants and through evaporation. Therefore, the water supply will need to be replenished occasionally. As a sustainable system, aquaponics allows for fast-growing fish stock that is less susceptible to disease.Purdue University (2009). “Aquaponics.” YouTube. 2009-10-27. However, regular observation is still required to maintain system and species health. Tilapia is the most common species raised in an aquaculture operation due to its rapid growth, large size and ability to live in high fish densities. Perch, trout, catfish and hybrid striped bass are also known to do well in the tank environment.Purdue University (2009). “Aquaponics.” YouTube. 2009-10-27. It is always safe to select a native species, which naturally require less maintenance. For example, Growing Power, a national nonprofit based in Milwaukee, produces 10,000 lake perch on a three-acre aquaponic system.“Our Community Food Center” (2010). Growing Power. Harvesting will be determined by individual species growth cycle and local regulation. The Water System (New Hydrologic Cycle) The removal and conversion of waste in tanks is the most important component of aquaponics. Where a strictly aquaculture system discards effluent (fluid waste), an aquaponic system recycles the water to promote the growth of fish.Purdue University (2009). “Aquaponics.” YouTube. 2009-10-27. The naturally occurring bacteria that break down waste do so in a process call anaerobic mineralization. These bacteria, collectively known as rhizobia, are typically found in root nodules. Markmann K, Giczey G, Parniske M (2008) Functional Adaptation of a Plant Receptor- Kinase Paved the Way for the Evolution of Intracellular Root Symbioses with Bacteria. PLoS Biol 6(3): e68 doi:10.1371/journal.pbio.0060068 Toxic materials in the water are broken down into useable forms of nitrogen, which plants require for proper development. Minerals such as iron and magnesium are frequently added to supplement the plants needs.Mensing, Blake M (2009). "Aquaponic & Landfill Methane Use." Sustainable Development Law & Policy 9.3. The Plant System (Hydroponics) Aquaponic systems are unique in that they require no soil. Growing beds may be soilless or use a growing medium such as gravel. Plants can grow in floating nets or mats. Plant roots are immersed in water absorbing the rich nutrients while filtering out compounds that are toxic to the fish.Purdue University (2009). “Aquaponics.” YouTube. 2009-10-27. The water is cycled through the growing medium to sustain the level of moisture needed for optimal plant growth. As a result, plants are constantly in contact with nutrient rich water. In the upper Midwest, where aquaponic systems are frequently indoors, an artificial light source is needed. The greenhouse model can also be used but is frequently supplemented by growing lights such as high-output fluorescents.Purdue University (2009). “Aquaponics.” YouTube. 2009-10-27. When growing plants under artificial lights, the heat output and cost efficiency are determinant of the species of plant used. The plant system generally brings a larger profit margin. Cabbage, herbs and vegetables are among the most common plants grown. And while insulation is required in most upper Midwest systems, watercress and tomatoes are the favorite crops for these economically viable systems.Purdue University (2009). “Aquaponics.” YouTube. 2009-10-27. Contact farmer’s markets in your area for information regarding the distribution and sale of crops grown in an aquaponic system: LocalHarvest.Org. ----